Eldorado - Repositorium der TU Dortmund
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Aktuellste Veröffentlichungen
Item type:Item, Highly efficient lithium extraction from magnesium-rich brines with ionic liquid-based collaborative extractants(2023-12-25) Yu, Gangqiang; Zhang, Xinhe; Hubach, Tobias; Chen, Biaohua; Held, ChristophSelective extraction of Li+ from high Mg2+/Li+ ratio brines with ionic liquid (IL) based collaborative extractants was investigated by experiments, thermodynamic analyses, and quantum chemical (QC) calculations. Effects of different IL cationic structures and organophosphorus ligands on extraction performances were studied. The results demonstrated that the system 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide + trioctyl phosphate ([HOEMIM][Tf2N] + TOP) was considered as the best extractant, with the very high extraction efficiency of Li+ (83.16 %) and separation selectivity of Li+/Mg2+ (742.11), which is higher than values reported in literature. The thermodynamic model ePC-SAFT was first extended to quantitatively predict the phase equilibria of the so-called “organic–inorganic complex strong electrolyte system” presented in this work. The molecular-level extraction mechanism was explored by QC calculation, indicating that the strong multi-site intermolecular interactions between Li+ and [HOEMIM][Tf2N] + TOP break the Li+ hydration. This work provides guidance to rationally design novel IL-based extractants for efficient extraction of Li+.Item type:Item, H2 production under stress: [FeFe]‑hydrogenases reveal strong stability in high pressure environments(2024-03-11) Edenharter, Kristina; Jaworek, Michel W.; Engelbrecht, Vera; Winter, Roland; Happe, ThomasHydrogenases are a diverse group of metalloenzymes that catalyze the conversion of H2 into protons and electrons and the reverse reaction. A subgroup is formed by the [FeFe]‑hydrogenases, which are the most efficient enzymes of microbes for catalytic H2 conversion. We have determined the stability and activity of two [FeFe]‑hydrogenases under high temperature and pressure conditions employing FTIR spectroscopy and the high-pressure stopped-flow methodology in combination with fast UV/Vis detection. Our data show high temperature stability and an increase in activity up to the unfolding temperatures of the enzymes. Remarkably, both enzymes reveal a very high pressure stability of their structure, even up to pressures of several kbars. Their high pressure-stability enables high enzymatic activity up to 2 kbar, which largely exceeds the pressure limit encountered by organisms in the deep sea and sub-seafloor on Earth.Item type:Item, How does corporate culture affect IPO price formation?(2024-03-25) Cumming, Douglas; Köchling, Gerrit; Neukirchen, Daniel; Posch, Peter N.We examine the relationship between corporate culture and initial public offering (IPO) price formation. Using a sample of 935 US IPOs and data on corporate culture from Li et al. (2021b), we find that IPOs of strong culture firms are associated with more positive price revisions and higher initial returns, i.e., more underpricing. These findings hold using an alternative measure of corporate culture, matched samples, and a large set of control variables. Consistent with key theories, the effects appear to be driven by underwriters deliberately compensating investors for revealing information about their perceptions of the firm's culture during bookbuilding.Item type:Item, Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 7/2026(Technische Universität Dortmund, 2026-03-17)Item type:Item, Reshaping anisotropic behavior in metallic sheets under complex stress states: symmetric and asymmetric polynomial models with advanced convexity analysis approach(2025-07-16) Ren, Yanqiang; Du, Kai; Hou, Yong; Song, Liying; Sun, Liang; Yang, Yanfeng; Zheng, Wentao; Yuan, XiaoguangFourth-order polynomial-related analytical symmetric and asymmetric anisotropic yield criteria under the non-associated flow rule, are proposed to cover a wider range of stress states. The new model can be directly calibrated using selected experimental data. Additionally, a modified geometry-inspired numerical convexity proof method is developed to demonstrate that the proposed model satisfies the convexity condition. Compared the newly proposed and existing advanced convexity proof methods and yield criteria, and evaluated the applicability and effectiveness of the new framework. The results indicate that the new convexity proof method provides highly accurate convexity identification, consistent with the Hessian matrix method, while maintaining the user-friendliness of the GINCA method. The new symmetric model exhibits the highest accuracy in characterizing the plastic anisotropy of DP490 and AA6016-T4 compared to other investigated yield criteria. Furthermore, the new asymmetric model effectively predicts the strength differential effect under complex stress states. Precise modeling of near-plane strain and pure shear stress states significantly enhances the characterization of stress states in tensile-tensile and tension–compression regions. Applying the anisotropic hardening concept enables continuous capture of the subsequent yielding behavior of metallic sheets.